Λ(1405) mediated triangle singularity in the K.sup.–./sup.d → pΣ.sup.–./sup. reaction

0565014 - ÚJF 2023 RIV US eng J - Článek v odborném periodiku
Feijoo, Aliau Eduardo Alberto - Molina, R. - Dai, L. - Oset, E.
Λ(1405) mediated triangle singularity in the K^–d → pΣ^– reaction.
European Physical Journal C. Roč. 82, č. 11 (2022), č. článku 1028. ISSN 1434-6044. E-ISSN 1434-6052
Grant CEP: GA ČR GA19-19640S
Institucionální podpora: RVO:61389005
Klíčová slova: Lambda(1405) * singularity * reactions
Obor OECD: Particles and field physics
Impakt faktor: 4.4, rok: 2022
Způsob publikování: Open access
https://doi.org/10.1140/epjc/s10052-022-10985-8

We study for the first time the p Sigma(-) -> K- d and K- d -> p Sigma(-) reactions close to threshold and show that they are driven by a triangle mechanism, with the Lambda(1405), a proton and a neutron as intermediate states, which develops a triangle singularity close to the (K) over bard threshold. We find that a mechanism involving virtual pion exchange and the K- p -> pi(+)Sigma(-) amplitude dominates over another one involving kaon exchange and the K- p -> K- p amplitude. Moreover, of the two Lambda(1405) states, the one with higher mass around 1420 MeV, gives the largest contribution to the process. We show that the cross section, well within measurable range, is very sensitive to different models that, while reproducing (K) over barN observables above threshold, provide different extrapolations of the (K) over barN amplitudes below threshold. The observables of this reaction will provide new constraints on the theoretical models, leading to more reliable extrapolations of the (K) over barN amplitudes below threshold and to more accurate predictions of the Lambda(1405) state of lower mass.
Trvalý link: https://hdl.handle.net/11104/0336578